Charles g



' I oemvANsf PISTON.

" (No Model.)

Patente d Oct 12., 1897.

ATTORNEYS.

. CHARLES o. EVANS,

PATENT OFFICE.

OF UNION, CANADA.

Pl STON.

SPECIFICATION forming part of Letters Patent No. 591,392, dated. October 12, 1897. A pli ti fil d December 14,1896- $eria1l1'o. 615,556- (ll'o model.)

To all whom it may concern.-

Be it known that I, CH RLES G. EVANS, of Union,- in the Province'of British Columbia and Dominion of Canada, have invented a new and Improved Piston, of which the following is a full, clear,'and exact description. The object of the invention is to provide a new and improved piston for steam-engines arranged to prevent all leakage of steam past the piston-packing and without undue friction of the packing-rin gs on the cylinder-wall. The invention consists of certain parts and details and combinations of the same, as will be fully described hereinafter and then pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification,

I in which similar characters of reference indicate corresponding parts in all the figures.

Figure 1 is a longitudinal section of the improvement. Fig.2 is a transverse sectionof the same on the line 2 2 of Fig. 1, and Fig. 3 is aplan view'of the ends of one of the packing-rings.

- The improved piston is provided with a piston-body A,.secured on a piston-rod B, connected in the usual manner with the drivingshaft of vthe engine, the piston being reciprocated in the cylinder 0 by the pressure of the steamor other motive agent alternately acting on the ends of the said piston.

On the front face of the piston-body A is arranged a follower D, fitted to slide longitudinally on the piston 13 and rigidly connected by rods orpins E with a follower D, held on the other face of the body A, the said rods or pins being fitted to slide in suitable hearings in the body A.. The follower D is connected by a series of longitudinallyextending rods F with a ring G, fitted to slide longitudinally in a recess A, formed in the body A, and the other follower D is similarly connected by rods F with a ring G, fitted to slide in a recess A likewise formed in the bod-yA- The rings G and G are formed on i t-heir peripheries with bevels engaging corresponding bevels on the inside of the packing-rings Hand H, extending through .the recesses A and A to engage the inside of the cylinder O and form a packing for the piston.

The packing-ring H is arranged near the face of the piston having the follower D, and the other packing-ring H is arranged near the face having the follower D, as is plainly shown insthe drawings, so that when the steam enters the right-hand end of the cylinder 0 and presses against the follower D then the latter moves to the left and. in doing so causes-a sliding of the other follower in the .same direction and a sliding of the rings G and G in the same direction to cause an expansion of the packing-ring H and a releasing of the packing-ring H.

When the steam enters the left-hand end of thecylinder C, it presses on the follower D, and'the latter is causedto slide to the right, carrying the follower D and the rings G G in the same direction, whereby the packing-ring H is expanded and the previouslyexpanded packing-ring H is released. Thus that side of the piston containing the exhaustdirectly actuating the expansion and releasing ring for the opposite side of the piston.

In order to limit the inward-sliding motion of the followers'D and D, I provide the inner faces of the followers D and D with beveled offsets D D respectively, engaging the inner bevels of rings I 1, respectively, held in annular'recesses A A respectively, formed in the body A. Guard-rings J J, secured on the piston-body, extend a short distance over the faces of the rings I I, so as to hold the same in their recesses against longitudinal movement. '1

The rings H H I I are made in the form of split rings, so as to permit of expanding the rings and allowing the same to contract by their own resiliency, the rings" H H being expanded by the movement of the rings G G,

respectively, and the rings I I being expanded by the beveled offsets D D respectively, onythe followers D and D. As shown in Fig. 8, each of the rings H H is formed at its split end with a dovetailed tongue H engaging a dovetailed recessed end H for securely connecting the ends with each other and still permit of expansion and contraction thereof for the purpose above described. The ends of the rings I I are similarly constructed.

Each of the pins Eis rigidly secured at one end to the follower D, and the other end is formed with a conical offset E, engaging a corresponding aperture in the follower D. The extreme outer end of the pin is formed with a right-hand screw-thread E and a lefthand screw-thread E of which the former is engaged by a nut K and the latter by a nut K, both having registering recesses K K countersunk at their adjacent ends and adapted to be filled with Babbitt metal or other material, which when cooled and set forms a locking-pin for securing the two nuts in position. A similar fastening is arranged for the pins or rods F F, which are secured at one end in the rings G G and at their other end by nut-locks, as described for the followers D D.

The expanding and releasing rings G G are preferably made in sections, of which the top section is made of very hard steel, the lower section of ordinary steel, and the side sections of soft iron, so that they wear readily and produce an oval ring-wedge which sets the packing-rings II H properly in a worn horizontal cylinder oval in cross-section. It is understood that the rings I I wear on their inner faces about in proportion to the wear of the packing-rings H H, so that an automatic adjustment always takes place as the offsets D D move farther inward on the rings I I, and consequently an expansion of the rings H H in a corresponding degree takes place, so as to insure at all times a perfect packing of the piston in the cylinder. The faces of the body A are recessed at A and A to permit the inner ends of the offsets D and D to move the desired distance when the followers are pressed inward by the motive agent.

By the arrangement described it is evident that the followers D D are pressed inward such a distance as the expansion of the rings I I allows, and consequently the rings H and II do not expand against the innersurface of the cylinder C according to the force or pressure of the steam, but only according to the amount of movement allowed by the said rings I and I, so that the rings are uniformly expanded with the inner wall of the cylinder 0 irrespective of the pressure of the motive agent in the ends of the cylinder as long as the pressure is sufficientfor shifting the followers, as above described. The rings I I, encircling the followers, give sufficient resistance to the followers to prevent the same from striking hard against their resting-surfaces when adjustment takes place.

Having thus fullydescribed my invention, I claim as new and desire to secure by Letters Patent 1. A piston, provided with packing-rings, and followers rigidly connected with each other and fitted to slide longitudinally by the pressure of the motive agent in the ends of the cylinder, the follower on one side of the piston being connected with the packing-ring for the other side of the piston, substantially as shown and described.

2. A piston, provided with packing-rings, followers rigidly connected with each other and fitted to slide longitudinally by the pressure of the motive agent in the ends of the cylinder, the follower on one side of the piston being connected with the packin g-rin g for the other side of the piston, and a device for limiting the sliding motion of the followers and the expansion of the rings, substantially as shown and described.

3. A piston, provided with packing-rings, a device for expanding and releasing each of the said packing-rings, and followers rigidly connected with each other and fitted to slide longitudinally, the follower on one side of the piston being rigidly connected with the expansion and releasing device on the other side of the piston, substantially as shown and described.

4. A piston, provided with packing-rings, a device for expanding and releasing each of the said packing-rings, followers rigidly connected with each other and fitted to slide longitudi-nally, the follower on one side of the piston being rigidly connected with the expansion and releasing device on the other side of the piston, and a limiting device for each follower, for limiting the sliding motion of the same, substantially as shown and described.

5. A nut-lock, comprising a rod havingright and left hand threads, and nuts on the said threads and formed with registering apertures adapted to be filled with a setting or hardening substance, the said apertures being countersunk at their adjacent ends, substantially as shown and described.

6. A piston, provided with an expansionring for the packing-ring, and made in sections of metal of different degrees of hardness, substantially as shown and described.

7. A piston having a body, a follower at each end of the body, two packing-rings running around the body, an expanding-ringbeneath each packing-ring, and connections respectively between the followers and the expanding-rings farthest therefrom, substantially as described.

8. A piston having a body, a follower at each end of the body, expansive packingrings, and connections respectively between the followers and the packing-rings farthest therefrom, whereby upon the movement of one follower the packing-ring farthest from said follower will be expanded, substantially as described.

9. A piston having a bod y, a follower thereon, an expansive packin g-ring, an expandingring having connection with the packing-ring and moving to expand the same, and a connection between the follower and the expanding-ring, substantially as described.

CHARLES G. EVANS.

Witnesses:

DONALD lllACKINZIE, FREDERICK IIAnwooD. 

